1. Field of the Invention
The invention relates to tapered roller bearings.
2. Description of Related Art
Although compact in size, tapered roller bearings are capable of supporting large radial and axial loads and usable in high speed rotation applications. Thus, tapered roller bearings are used for a wide range of purposes.
As illustrated in FIG. 6, a tapered roller bearing 90 includes an inner ring 99, an outer ring 98, a plurality of tapered rollers 96, and an annular cage 95 (see Japanese Patent Application Publication No. 2015-52349 (JP 2015-52349 A)). The inner ring 99 includes an inner raceway surface 99a tapered so that the inner ring 99 increases in outside diameter from a first axial side S1 to a second axial side S2. The outer ring 98 includes an outer raceway surface 98a tapered so that the outer ring 98 increases in bore diameter from the first axial side S1 to the second axial side S2. The tapered rollers 96 are provided in an annular space 97 defined between the inner raceway surface 99a and the outer raceway surface 98a. The cage 95 retains the tapered rollers 96.
Rotation of the tapered roller bearing 90 produces a pumping effect by which lubricant flows through the inner space of the tapered roller bearing 90 (i.e., the annular space 97) from the first axial side S1 to the second axial side S2 (see the arrows J in FIG. 6). Unfortunately, such a pumping effect may increase lubricant agitation resistance during bearing rotation, which results in an increase in torque, or may discharge the lubricant from the first axial side S1 to the second axial side S2, causing a lubricant shortage in a portion of the tapered roller bearing 90 on the first axial side S1 where the lubricant is necessary.